Enabling technologies Pierre GAYRAUD THALES Avionics ASAS-TN Seminar Brighton October 2004

Content ASAS ADS-B ADS-B Data Links Mode S Extended Squitter VDL Mode 4 UAT TIS-B On-board Sensors, Processing & Display

ASAS Enabling technologies ASAS Display ADS-B ADS-B receiver ground station TIS-B Aircraft Sensors

ASAS Functional description On-board systems and data sources (FMS, GPS, pilot interface) Airborne data processing, Display Applications processing ACAS Aircraft N ADS-B out ADS-B in On-board systems and data sources (FMS, GPS, pilot interface) Airborne data processing, Display Applications processing ACAS Aircraft A ADS-B out ADS-B in Navigation information - any source including GPS Ground vehicle ADS-B out Ground systems Ground ADS-B receiver ATC surveillance Controller Working Position

ADS-B Definition ADS-B: « Automatic Dependent Surveillance – Broadcast » « A function on an aircraft or surface vehicle that broadcasts position, altitude, vector and other information for use by other aircraft, vehicles and by ground facilities » (Draft ICAO ASAS Circular) The broadcast is independent of any external stimuli The originating aircraft does not know who receives and uses its broadcast Users: surrounding aircraft/vehicle and/or ATC Three candidate data link technologies –Secondary surveillance radar (SSR) Mode S Extended Squitter (SSR Mode S ES) –VHF digital link Mode 4 (VDL Mode 4) –Universal Access Transceiver (UAT)

ADS-B Message content Data transmit by ADS-B generically defined by RTCA ADS-B MASPS DO-242A –Horizontal position and related data –Lat/Long, Horizontal velocity, Ground speed, Heading on surface –Integrity (Navigation Integrity Category, Surveillance Integrity Level ) –Optional: Airspeed, Heading while airborne –Altitude and related data –Barometric altitude, Geometric altitude, Vertical rate, NIC baro –Status –ICAO address, Call sign, Emitter category, Length and width –Emergency/priority, Capability class codes –Target State: Target altitude and HDG/TRK –Trajectory Change (Under review) Arrangement within one or several transmissions according to the data link technology

ADS-B ICAO data link policy Air Navigation Conference (2003) Recommendations Strategy for the near-term –ICAO encourages the selection of the SSR Mode S Extended Squitter as the initial data link –Regional implementations Europe: VDL Mode 4 US: UAT In the longer term –The current SSR Mode S extended squitter technology may not be able to fully satisfy all of the requirements for ADS-B services in all airspaces –Continue to develop standards for ADS-B link technologies, including VDL Mode 4 and UAT

SSR Mode S ES Main characteristics (1) On 1090 MHz channel –Secondary Surveillance radar (SSR) Mode A and C –Aircraft SSR Mode S responses to interrogations from ground-based radars Aircraft answers to ACAS interrogations including transmission of non-solicited answers ADS-B SSR Mode S Extended Squitters Based on (except Modes A and C) –Multiple Access: pseudo random timing of the transmissions –Pulses modulated at 1 MHz able to convey 56 or 112-bit messages –Downlink and Uplink predefined formats

SSR Mode S ES Main characteristics (2) Squitters –Aircraft broadcast non-solicited long squitters (112 bits) –Data to be transmit are prepared in « registers » –Different types of SSR Mode S Extended Squitters Airborne/Surface Position Squitter Content of registers 05/06 (rate: 0.5 s) Airborne Velocity Squitter: register 09 rate: 0.5 s Aircraft Identification Squitter: register 08 Event-Driven Squitter: register 0A => Several Squitters are necessary to transmit data

SSR Mode S ES Standardisation status ICAO SARPS: Annex 10 Vol III Ch 5 and Vol 4 –The current standard is Amdt 77 –Plans to modify the content of some registers in order to improve the characterisation of the safety level RTCA MOPS –DO-260: Minimum Operational Performance Standards for 1090 MHz ADS-B –DO-260A: with proposed improvements on safety level characterisation

SSR Mode S ES Transmitters On-board current Transponders –Mode S transponders transmit on 1090 MHz aircraft SSR Mode S responses to interrogations from ground-based radars –They are installed on most aircraft (mandatory on all IFR aircraft in Europe as of 31/03/2005) Evolution towards ADS-B Out Transmitters –Transmission of Extended Squitters is part of the standard (provided Registers are loaded by the avionics)

SSR Mode S ES On-board Receivers Current TCAS –The TCAS box includes a 1090 MHz reception function of answers of surrounding aircraft to ACAS interrogations short squitters Evolution towards ADS-B receiver –SSR Mode S Extended Squitters can be received and extracted by TCAS –Independency between TCAS and SSR Mode S Extended Squitters reception is required: no common failure

VDL Mode 4 Main characteristics Frequency Band : MHz (i.e. Nav and Comm bands) Bandwidth : 25 KHz per channel Time Division Multiple Access, self organised by the mean of a common clock available to all users : UTC time (GPS) VDL4 user terminal checks available slots and make reservations in subsequent frames for transmission The VDL Mode 4 protocol allows to manage several VHF channels –2 Global Signalling Channels (GSC) –Regional and Local Signalling Channels (LSC) for additional services as required 4500 slots/minute Bit rate : 19,200 bits/s

VDL Mode 4 Standardisation Status ICAO SARPS: Annex 10 Vol III Ch Manual on VHF Digital Link (VDL) Mode 4 Airborne MOPS: ED-108A in preparation Ground: on-going ETSI standardisation

UAT Main characteristics Designed specifically for ADS-B with no constraints from legacy systems Single common wideband channel 2-3MHz 1 Mbps channel rate in MHz (ARNS band) Aircraft access the channel autonomously at random Transmission rate: 1/sec.

UAT Status Standardisation status –Frequency allocation: need to be co-ordinated on a world-wide basis –SARPs not yet available –MOPS available (DO-282) Product status –UAT part of SafeFlight-21 Link Evaluation study –UAT selected by FAA Alaska Region ( installations in Western Alaska)

TIS-B Definition TIS-B « A service provided by ground stations, broadcasting information relating to aircraft based on surveillance carried out by ground systems, using ADS-B signals, formats and protocols, compatible with ADS-B receiving equipment » (Draft ICAO ASAS Circular) Data link technologies identical to ADS-B Depends on a ground surveillance infrastructure –e.g. SSR, PSR, ADS-B, multilateration, ASDE Users: surrounding Aircraft/Vehicle

TIS-B Role & Status Role –Provides aircraft with a complete picture of the traffic –Exact role to be defined (ADS-B gap filler, ADS-B data validation, Bridge between different ADS-B data link technologies, Primary source for some ASAS applications?) Status –Elements in ICAO SARPS for SSR Mode S Extended Squitters and VDL Mode 4 technologies –Complete SARPS to be developed –RTCA MASPS DO-280

On-board Sensors ADS-B requires on-board availability of –Aircraft position May be based on GPS or FMS multisensor position Available on all RNAV capable aircraft Integrity data from GPS (more difficult with FMS) –Altitude and related data –Barometric altitude: always available –Geometric altitude: if GPS –Status Ident: ICAO address and Call sign may require specific Control Panel

On-board Processing Surveillance layerApplications layer Data Link layer Display Surveillance Data Processing Own position Other Systems (FMS, MCDU…) ASAS tracks ASAS tracks, Selected target, Guidance data Display Management ASAS Applications TA/RA ACAS tracks TA/RA ACAS tracks CAS LogicACAS Surveillance Active reply Active Interrog UAT / VDL M4 Receivers ADS-B TIS-B 1090 MHz Receiver

On-board Display Cockpit Display of Traffic Information (CDTI) –Example of Navigation (FMS), TCAS and ASAS sharing the same display